In the obtaining metals from their ores, such as the processing of tungsten bearing ores to obtain the tungsten values therefrom, a quantity of a waste sludge is generated. This waste material contains low levels of various metals.
U.S. Pat. No. 4,624,703 issued Nov. 25, 1986 and assigned to GTE Products Corporation, discloses a process for recovering tungsten, scandium, iron and manganese from a tungsten bearing material via a solvent extraction process using a dialkyl phosphoric acid to extract the scandium. U.S. Pat. No. 4,624,703 is incorporated by reference herein.
U.S. Pat. No. 4,626,280 issued Dec. 2, 1986 and assigned to GTE Products Corporation discloses another process for recovering tungsten, scandium, iron and manganese from a tungsten bearing material via a process in which the material is digested in an aqueous sulfur dioxide solution and a tertiary alkyl primary amine is used as an extracting agent for the scandium. U.S. Pat. No. 4,626,280 is incorporated by reference herein.
U.S. Pat. No. 4,718,995 issued Jan. 12, 1988 and is assigned to GTE Products Corporation is a continuation-in-part of the aforementioned U.S. Pat. No. 4,626,280 and discloses using sulfuric acid and a reducing agent to digest the tungsten bearing material. U.S. Pat. No. 4,718,995 is incorporated by reference herein.
U.S. Pat. No. 4,718,996 issued Jan. 12, 1988 assigned to GTE Products Corporation is a continuation-in-part of U.S. Pat. No. 4,624,703, mentioned above. U.S. Pat. No. 4,718,996 discloses the additional aspect of using a sulfur dioxide aqueous solution to digest the tungsten bearing material. U.S. Pat. No. 4,718,996 is incorporated by reference herein.
U.S. Pat. No. 4,808,384 issued Feb. 28, 1989 assigned to GTE Products Corporation relates to the process disclosed in U.S. Pat. No. 4,624,703 mentioned above. U.S. Pat. No. 4,808,384 discloses the additional aspect of using coal as a reducing agent in the digestion step and is incorporated by reference herein.
An additional process that will recover essentially all of the valuable metal values from the waste material without the generation of hazardous or toxic materials is an advancement in the art.